Reconstitution math for research peptides

Mass, volume and concentration are one equation. A worked reference for converting a vial's milligrams into a working solution of known micrograms-per-microliter, with the unit traps that cause most bench errors.

Reconstitution is arithmetic with units: concentration equals mass divided by volume. Every bench error we see in shared protocols traces to a unit slip — milligrams read as micrograms, milliliters as microliters — not to the arithmetic itself.

The one equation

C = m / V. A 10 mg vial brought to 2 mL holds 5 mg/mL, which is 5 µg/µL. Aliquoting 100 µL of that solution delivers 500 µg of peptide mass. Writing the units on every line of the calculation is the entire safety practice.

Worked example

Vial: 10 mg lyophilized peptide.
Diluent: 2.0 mL bacteriostatic water (research handling).
Concentration: 10 mg / 2.0 mL = 5 mg/mL = 5 µg/µL.
Aliquot for a 250 µg mass: 250 µg / 5 µg/µL = 50 µL.

The traps

mg vs µg: a factor of 1,000. Write both forms until the habit is fixed.
mL vs µL: another factor of 1,000, in the volume term.
Peptide mass vs salt mass: certificates report peptide content; the vial's gross mass includes counterions and residual water.
Head-space and recovery: the last 50 µL of a vial is where adsorption losses concentrate.

For laboratory planning only. Stratum Biologic sells research materials; nothing here is administration guidance.

RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL USE.